Olympic gold medalist Caitlyn Jenner says not telling her father the truth about her gender identity “will always haunt me.”

The Philadelphia Inquirer reports that Jenner says she also was unsure how her mother would react to her transition from a man to a woman. But she says her mother has since become her “best ally” even if she sometimes calls her Bruce.

Jenner spoke before a sold-out crowd at the University of Pennsylvania Wednesday about her struggle with gender dysphoria.

She discussed her relationships with her ex-wives and children and says she contemplated suicide when news she was considering trachea surgery surfaced. But she broke into tears, saying her biggest regret was not being truthful with her now-deceased father.